TWI659338B - Display device having a touch-input function - Google Patents

Abstract

An object of an embodiment is to provide a novel electronic device configured so that a user can read data regardless of location, touch the keyboard displayed on the screen by direct contact or touch the keyboard with a stylus or the like. To enter data and use input data. The electronic device includes a first transistor electrically connected to the reflective electrode and a light sensor above the flexible substrate. The touch input button is displayed as a still image on the first screen area of the display section, and a video signal is output to display a moving image on the second screen area of the display section. The video signal processing section is provided to supply different signals between a case where a still image is displayed on the display section and a case where a moving image is displayed on the display section. After the writing of the still image is performed, the display element control circuit is put into a non-operation state, thereby reducing power consumption.

Description

Display device with touch input function

The present invention relates to an electronic device having a circuit including a transistor and an electronic system. For example, the present invention relates to an electronic device on which a photovoltaic device, typically a liquid crystal display panel, is mounted as a component.

In recent years, display devices such as e-book readers have been actively developed. In particular, since a technology in which a display element having a memory property is used to display an image greatly contributes to a reduction in power consumption, this technology has been actively developed (Patent Document 1).

In addition, a display device provided with a touch sensor has attracted attention. A display device provided with a touch sensor is referred to as a touch panel, a touch screen, or the like (hereinafter also simply referred to as a touch panel). In addition, Patent Document 2 discloses a display device on which an optical touch sensor is mounted.

[Quote] [Patent Literature]

[Patent Document 1] Japanese Published Patent Application No. 2006-267982

[Patent Document 2] Japanese Published Patent Application No. 2001-292276

An object of an embodiment is to provide an electronic device that is light and flexible, and improves the impact resistance by using a flexible film as a substrate instead of a hard substrate such as a glass substrate.

In addition, an object of an embodiment is to provide a driver circuit, which is advantageous for saving energy of an electronic device (such as a portable information terminal) with limited power.

An object of an embodiment is to provide a novel electronic device configured to allow a user to read data regardless of location, by directly touching a keyboard displayed on the screen with a stylus or by using a stylus or the like. Use the keyboard to enter data and use the input data. An object of an embodiment is to provide a pixel structure in which a light receiving area of a light sensor and a pixel electrode area per unit area are increased to obtain an electronic device configured to allow a user to read data and use the touch Enter the data by touching the keyboard displayed on the screen.

In addition, an object of an embodiment is to provide a novel electronic device in which a still image mode and a moving image mode including a keyboard display are implemented on a screen.

In addition, an object of an embodiment is to reduce power consumption in a manner such that, in the case of the still image mode, a still image is displayed on a part of the display section, and then stopped in the area where the still image is displayed until the Power supply, and a state in which still images can be seen for a long time after the supply is stopped.

In an electronic device including a display section in which an image is displayed using external light, the display section has a touch input function using a light sensor to display a keyboard button on at least a part of the display section, and the user touches a desired one by touching To enter data, press the key to enter the data. Therefore, the display corresponding to the desired key is executed on the display.

The light sensor detects external light that enters the display portion when the user points a desired position on the display device and a shadow (hereinafter referred to as a partial shadow of external light) made on a portion of the display portion. The input processing section processes the position of the light sensor that detects a partial shadow of external light on the display section as the coordinate position of the touch input. The video signal processing section outputs coordinates corresponding to the touch input, that is, data of the keyboard, as image data to the display section.

The first display area on which the keyboard is displayed displays a still image during a period in which the user inputs data with the keyboard displayed on the display section. When the user inputs data, the second display area displays a moving image in a period in which letters or numbers corresponding to the touched keys are written one after another or in a period in which letter conversion is performed.

An embodiment of the present invention disclosed in this specification is an electronic device including a video signal processing unit that switches a first screen area of a display portion to a screen area on which touch input is performed or an output thereon. To display the screen area. Alternatively, the electronic device includes a video signal processing section that supplies different signals to the display elements of the display section between a case where a still image is displayed on the display section and a case where a moving image is displayed on the display section. After the writing of the still image is performed, the display element control circuit is put into a non-operation state, thereby reducing power consumption. In particular, it is preferable to use a decoder circuit as the scan line driver circuit.

The switching transistor included in the conventional active matrix type display device has a problem that even when the transistor is in an off state, the off current is large and a signal written to a pixel leaks out. According to an embodiment of the present invention, by using a transistor including an oxide semiconductor layer as a switching transistor, the off-state current is extremely small. In particular, the off-state current density per channel width of 1 μm at room temperature may be less than or equal to 10 aA ( 1 × 10 ^-17 A / μm), further, less than or equal to 1 aA (1 × 10 ^-18 A / μm), or even more, less than or equal to 10 zA (1 × 10 ^-20 A / μm). In addition, in pixels, the holding time of an electric signal such as a video signal is longer, and the interval of the writing time can be set to be long. Therefore, by using a transistor including an oxide semiconductor, a period during which the display element control circuit is in a non-operation state after writing a still image can be extended, thereby further reducing power consumption.

An embodiment of the present invention for implementing an electronic device is an electronic device including a display portion having a touch input function; a first transistor electrically connected to a reflective electrode; and a light sensor above a flexible substrate. In the electronic device, the light sensor includes a photodiode, a second transistor including a gate signal line electrically connected to the photodiode, and a third transistor. In the electronic device, one of the source and the drain of the second transistor is electrically connected to the light sensor reference signal line, and the other of the source and the drain of the second transistor is electrically connected to the third transistor. One of the source and the drain, and the other of the source and the drain of the third transistor is electrically connected to the photo-sensor output signal line.

With the above structure, at least one of the above problems can be solved.

In the above structure, the oxide semiconductor layer of the second transistor overlaps the read signal line, and a gate insulating layer is disposed therebetween, and the read signal line overlaps as a reflective electrode of a pixel electrode. With the pixel structure in which the read signal line and the third transistor are disposed under the reflective electrode, the light receiving area and the pixel electrode area (hereinafter, referred to as the reflective electrode area) of the light sensor per unit area can be effectively used.

In addition, an embodiment of the present invention is an electronic device including a display portion having a touch input function; and a first transistor electrically connected to the first reflective electrode and a second transistor electrically connected to the second reflective electrode, And the light sensor is above the flexible substrate. In the electronic device, the light sensor includes a photodiode, a third transistor including a gate signal line electrically connected to the photodiode, and a fourth transistor. In the electronic device, one of the source and the drain of the third transistor is electrically connected to the light sensor reference signal line, and the other of the source and the drain of the third transistor is electrically connected to the fourth transistor. One of the source and the drain, and the other of the source and the drain of the fourth transistor is electrically connected to the photo-sensor output signal line. In an electronic device, an oxide semiconductor layer of a fourth transistor overlaps the first reflective electrode, and a photo-sensor reference signal line overlaps the second reflective electrode.

The above structure is designed so that when the pixel structure is viewed from above, a light receiving area of a light sensor is provided between the two reflective electrodes, thereby effectively using the light receiving area and the reflective electrode area of the light sensor per unit area.

In the above structure, the oxide semiconductor layer of the third transistor overlaps the read signal line, and a gate insulating layer is provided therebetween, and the read line overlaps the first reflective electrode. With the pixel structure in which the read signal line and the fourth transistor are disposed below the first reflective electrode, the light receiving area and the reflective electrode area of the light sensor per unit area can be effectively used.

In any of the above structures, one of the source and the drain of the fourth transistor overlaps the first reflective electrode and the other of the source and the drain of the fourth transistor overlaps the second reflective electrode. With this pixel structure, the light receiving area and reflection area of the light sensor per unit area can be effectively used.

In addition, in the above-mentioned structure, a color filter is provided to overlap the first reflective electrode or the second reflective electrode, whereby full-color display can also be performed.

In addition, the reflective liquid crystal device contributes to energy saving, because even when a backlight is not provided, external light (such as sunlight or illumination light) can be used to recognize the displayed content.

A portable information terminal capable of displaying moving images and still images on one screen. The driving and supply of signals are performed differently between the case where a moving image is displayed on the screen area and the case where a still image is displayed on the screen area, and the power consumption for displaying a moving image can be reduced compared to the power consumption for displaying a still image. the amount. In addition, since the reflection type liquid crystal display device is used, halftone display in gray scale can be performed, and the gradation range is wider than that in the case of the electrophoretic type display device.

In addition, by using a portable information terminal that uses a flexible substrate to reduce weight, users can read data regardless of location, and input data by touching the keyboard displayed on the screen, so they can be on it The result of the input is displayed on the screen showing the keyboard.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that the modes and details disclosed herein can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the examples.

[Example 1]

In this embodiment, an example of an electronic device including a display portion in which an image is displayed using external light is described with reference to FIGS. 1A and 1B.

The display portion 1032 of the electronic device 1030 has a touch input function using a light sensor. A plurality of keyboard buttons 1031 are displayed on an area 1033 in the display portion, as shown in FIG. 1A. The display portion 1032 indicates the entire display area and an area 1033 included in the display portion. The user inputs data by touching a desired keyboard button, and thereby displays the input result on the display portion 1032.

Since a still image is displayed in the area 1033 in the display section, power consumption can be reduced by placing the display element control circuit in a non-operation state during periods of non-writing time.

An example of the use of the electronic device 1030 is described. For example, a user's finger successively touches a keyboard button displayed on a region 1033 in the display unit or enters a letter without contact, and displays text on a region other than the region 1033 in the display unit to display the result as an input. After the user has moved his / her finger away from the keyboard of the screen without detecting the output signal of the light sensor for a set period of time, the keyboard displayed on the area 1033 is automatically removed and the area also in the display portion The input text is displayed on 1033. In the case where the input is performed again, a keyboard button can be displayed again on the area 1033 in the display portion by touching the display portion 1032 or the output signal of the non-contact detection light sensor with the user's finger, and can be executed. Entering letters.

Alternatively, the keyboard can be removed non-automatically by the user pressing the switch 1034 to display a still image on the entire display portion 1032, as shown in FIG. 1B. In addition, even when the power is turned off by pressing the power switch 1035, a still image can be maintained for a long time. In addition, the keyboard can be displayed in a state where touch input can be performed by pressing the keyboard display switch 1036.

In addition, each of the switches 1034, the power switch 1035, and the keyboard display switch 1036 can be displayed on the display unit 1032 as switch buttons. Each operation can be performed by touching the displayed switch button.

In addition, the structure in which a still image is displayed in the area 1033 in the display section is not limited, and the area 1033 in the display section may temporarily or partially display a moving image. For example, the position of the display keyboard can be temporarily changed according to the user's preference, or when the input is performed contactlessly, the display of the keyboard buttons corresponding to the entered letters can be partially changed to confirm whether the input is performed.

The electronic device 1030 includes at least one battery, and preferably includes a memory (such as a flash memory circuit, a SRAM circuit, or a DRAM circuit), a central processing unit (CPU), or a logic circuit for storing data. Various software can be installed by the CPU or the memory and therefore, the electronic device 1030 can have a part or all of the functions of a personal computer.

In addition, by providing a gradient detection section such as a gyroscope or a three-axis acceleration sensor in the electronic device 1030, the function used in the electronic device 1030 can be switched by an arithmetic circuit according to a signal from the gradient detection section. In particular, regarding the Display functions and inputs on the display. Therefore, unlike an electronic device with an input key of a predetermined type, size, or configuration, such as a built-in operation key, the electronic device 1030 can improve convenience for the user.

Next, an example of a display panel included in the display section 1032 will be described with reference to FIG. 2. The display panel 100 includes a pixel circuit 101, a display element control circuit, and a light sensor control circuit. The pixel circuit 101 includes a plurality of pixels 103 and 104 and a complex light sensor 106 arranged in a matrix of columns and rows. Each of the pixels 104 and 103 includes a display element. Although a light sensor 106 is provided between the pixels 103 and 104 in this embodiment, and the number of the light sensors is half of the number of pixels, the embodiment is not limited thereto. A light sensor can be set for each pixel, so the number of light sensors is the same as the number of pixels. Alternatively, the number of light sensors may be a third of the number of pixels.

The display element 105 includes a liquid crystal element or the like including a transistor, a storage capacitor, and a liquid crystal layer. The transistor has a function of controlling the injection of electric charge into or from the storage capacitor. The storage capacitor has a function of holding a charge corresponding to a voltage applied to the liquid crystal layer. The contrast (gray scale) of light passing through the liquid crystal layer is manufactured by changing the direction of polarization due to the application of a voltage to the liquid crystal layer, so that image display is realized. External light (sunlight or illumination light) entering from the surface side of the liquid crystal display device is used as light passing through the liquid crystal layer. The liquid crystal layer is not particularly limited, and a known liquid crystal material (typically, a nematic liquid crystal material or a cholesteric liquid crystal material) can be used. For example, a polymer dispersed liquid crystal (PDLC) or a polymer network liquid crystal (PNLC) can be used as the liquid crystal layer, so white display (light display) can be performed by the liquid crystal using scattered light. When PDLC or PNLC is used as the liquid crystal layer, there is no need for a polarizing plate and a display close to paper, which is eye-friendly and causes less tiredness.

In addition, the display element control circuit is a circuit configured to control the display element 105 and includes a display element driver circuit 107 that inputs a signal to the display element 105 through a signal line (also referred to as a source signal line) such as a video data signal line, and The display element driver circuit 108 inputs signals to the display element 105 through a scanning line (also referred to as a gate signal line).

For example, the display element driver circuit 108 on the scanning line side has a function of selecting display elements included in pixels placed in a specific column. The display element driver circuit 107 on the driving signal line side has a function of applying a predetermined potential to the display elements included in the pixels placed in a specific column. Note that in the display element where the display element driver circuit 108 on the scanning line side applies a high potential to it, the transistor is in an on state, so the display element is supplied with the electric charge from the display element driver circuit 107 on the signal line side.

The light sensor 106 includes a transistor and a light receiving element, and has a function of generating an electric signal when receiving light, such as a photodiode.

The light sensor control circuit is a circuit configured to control the light sensor 106 and includes a signal line for the light sensor output signal line, a light sensor reference signal line, or the like on the signal line. Circuit 109, and a light sensor driver circuit 110 on the scan line side. The light sensor driver circuit 110 on the scanning line side has a function of performing a reset operation and selecting an operation of the light sensor 106 included in the pixels placed in a specific column, which will be described below. In addition, the light sensor reading circuit 109 on the signal line has a function of taking out an output signal of the light sensor 106 included in the pixels in the selected column.

Referring to FIG. 3, circuit diagrams of the pixel 103, the light sensor 106, and the pixel 104 are described in this embodiment. The pixel 103 includes a liquid crystal element 105 including a transistor 201, a storage capacitor 202, and a liquid crystal layer 203. The light sensor 106 includes a photodiode 204, a transistor 205, and a transistor 206. The pixel 104 includes a liquid crystal element 125 including a transistor 221, a storage capacitor 222, and a liquid crystal layer 223.

The gate of the transistor 201 is electrically connected to the gate signal line 207. One of the source and the drain of the transistor 201 is electrically connected to the video data signal line 210, and the other of the source and the drain of the transistor 201 is electrically connected. One electrode of the storage capacitor 202 and one electrode of the liquid crystal element 203. The other electrode of the storage capacitor 202 is electrically connected to the capacitor wiring 214 and is maintained at a fixed potential. The other electrode of the liquid crystal element 203 is maintained at a fixed potential. The liquid crystal element 203 is an element including a pair of electrodes, and a liquid crystal layer is provided between the pair of electrodes.

When the potential "high (H)" (high potential) is applied to the gate signal line 207, the transistor 201 applies the potential of the video data signal line 210 to the storage capacitor 202 and the liquid crystal element 203. The storage capacitor 202 maintains the applied potential. The liquid crystal element 203 changes light transmittance according to an applied potential.

One of the electrodes of the photodiode 204 is electrically connected to the photodiode reset signal line 208, and the other electrode of the photodiode 204 is electrically connected to the gate of the transistor 205. One of the source and the drain of the transistor 205 is electrically connected to the light sensor reference signal line 212, and the other of the source and the drain of the transistor 205 is electrically connected to the source and the drain of the transistor 206. One. The gate of the transistor 206 is electrically connected to the read signal line 209, and the other of the source and the drain of the transistor 206 is electrically connected to the photo sensor output signal line 211.

The gate of the transistor 221 is electrically connected to the gate signal line 227. One of the source and the drain of the transistor 221 is electrically connected to the video data signal line 210. The other of the source and the drain of the transistor 221 is electrically connected. One of the electrodes connected to the storage capacitor 222 and one of the electrodes of the liquid crystal element 223. The other electrode of the storage capacitor 222 is electrically connected to the capacitor wiring 224 and is maintained at a fixed potential. The other electrode of the liquid crystal element 223 is maintained at a fixed potential. The liquid crystal element 223 includes a pair of electrodes and a liquid crystal layer is provided between the pair of electrodes.

Next, an example of the structure of the light sensor reading circuit 109 will be described with reference to FIGS. 3 and 4. For example, the display unit includes pixels arranged in 1024 columns and 768 rows. A display element is provided in each pixel in one column and one row, and a light sensor is provided between two pixels in two columns and one row. That is, display elements are provided in 1024 columns and 768 rows, and light sensors are provided in 512 columns and 768 rows. In addition, this embodiment describes an example in which output to the outside of the display device is performed in a case where the light sensor output signal lines in two rows are regarded as a pair. That is, an output is obtained from two light sensors arranged between four pixels in two columns and two rows.

Figure 3 shows the circuit configuration of the pixels, which shows two pixels and two pixels in one row and one light sensor. A display element is disposed in a pixel and a light sensor is disposed between the two pixels. FIG. 4 shows a circuit configuration of the light sensor reading circuit 109, and some light sensors are shown for the sake of explanation.

As shown in Fig. 4, consider an example of a driving method in which a scanning line driver circuit of a light sensor simultaneously drives four rows of pixels (that is, two rows of light sensors) and is selected by one row displacement Columns, including light sensors corresponding to two columns of pixels. Here, the light sensor in each column is continuously selected during a period in which the selected line is shifted twice by the scan line driver circuit. This driving method helps to improve the frame frequency when imaging by a light sensor. This is particularly advantageous in the case of a large-sized display device. Note that the outputs of the light sensors in the two columns are superimposed on the light sensor output signal line 211 at a time. All light sensors can be driven by repeating the displacement of the selected column 512 times.

As shown in FIG. 4, in the light sensor reading circuit 109, a selector is provided for each pixel of the 24 columns. The selector selects one pair of photo sensor output signal lines 211 (one pair corresponding to two rows of photo sensor output signal lines 211) in the display section and obtains an output. In other words, the light sensor reading circuit 109 includes a total of 32 selectors and obtains 32 outputs at a time. The selection is performed on all 12 pairs in each selector, whereby a total of 384 outputs can be obtained, which corresponds to a column of light sensors. Each time the selected line is shifted by the scan line driver circuit of the light sensor, the selector selects a pair from 12 pairs, thereby obtaining the output from all the light sensors.

In this embodiment, as shown in FIG. 4, consider the following structure: the light sensor reading circuit 109 on the signal line side takes out the output of the light sensor, which is an analog signal to the outside of the display device , And an amplifier provided outside the display device is used to amplify the outputs and convert them into digital signals using an AD converter. Of course, the following structure may be adopted: the AD converter is mounted on the substrate on which the display device is disposed, and the output of the light sensor is converted into a digital signal and then the digital signal is taken out to the outside of the display device.

In addition, the operations of the individual light sensors are realized by repeating the reset operation, the accumulation operation, and the selection operation. "Reset operation" means an operation in which the potential of the photodiode reset signal line 208 is set to "H". When the reset operation is performed, the photodiode 204 is brought into conduction, and the potential of the gate signal line 213 connected to the gate of the transistor 205 is set to "H".

The “cumulative operation” means an operation in which the potential of the photodiode reset signal line 208 is set to a potential “low (L)” (low potential) after the reset operation. Further, the "selection operation" means an operation in which the potential of the read signal line 209 is set to "H" after the accumulation operation.

When the accumulation operation is performed, when the light irradiating the photodiode 204 becomes strong, the potential of the gate signal line 213 connected to the gate of the transistor 205 is reduced, and the channel resistance of the transistor 205 is increased. Therefore, when the selection operation is performed, the current flowing to the photo sensor output signal line 211 via the transistor 206 is small. On the other hand, when the light irradiating the photodiode 204 is weak during the accumulation operation, the current flowing to the light sensor output signal line 211 via the transistor 206 is increased during the selection operation.

In this embodiment, when a reset operation, an accumulation operation, and a selection operation are performed on the light sensor, a partial shadow of external light may be detected. In addition, when image processing or the like is appropriately performed on the detected shadow, a position where a finger, a stylus pen, or the like touches the display device can be recognized. For the operation of inputting a letter corresponding to the position where the display device is touched, the type of the letter is regulated in advance, so that a desired letter can be input.

Note that in the display device in this embodiment, a partial shadow of external light is detected by a light sensor. Therefore, even if a finger, stylus, or the like does not actually touch the display device, when a finger, a stylus, or the like approaches the display device without contact and forms a shadow, the detection of the shadow is feasible. Thereafter, the "finger, stylus, or the like touching the display device" includes a case where a finger, a stylus, or the like approaches the display device without contact.

With the above structure, the display portion 1032 can have a touch input function.

In the case of performing touch input, the display device has a structure in which a display portion includes an image of a still image (such as a keyboard), and a finger or a stylus touches a position where a keyboard or a desired letter is displayed to perform input, thereby improving Operability. In the case of implementing the display device, the power consumption in the display device can be greatly reduced in the following manner. That is, in the first screen area where a still image is displayed on the display section, it is effective to stop supplying power to the display element in the first screen area after displaying the still image and keep the state of the still image visible for a long time after stopping the supply. In the second screen area which is the remaining display section, for example, the result from the touch input is displayed. The display element control circuit is in a non-operation state during a period when the display image in the second screen area is not updated, thereby saving power. The driving method that enables the above control is described below.

For example, FIG. 5 shows a timing diagram of a shift register of a scan line driver circuit in a display device including a display portion (where the display elements are arranged in 1024 columns and 768 rows). The period 61 in FIG. 5 corresponds to one cycle (64.8 microseconds) of the clock signal. The period 62 corresponds to a period (8.36 milliseconds) required to complete writing of the display elements from the 1st to 512th columns corresponding to the second screen area. The period 63 corresponds to a frame period (16.7 milliseconds).

Here, the displacement register of the scanning line driver circuit is a four-phase clock type displacement register, which is operated by the first clock signal CK1 to the fourth clock signal CK4. In addition, the first clock signal CK1 to the fourth clock signal CK4 are sequentially delayed by a quarter of a cycle period. When the start pulse signal GSP is set to "H", the gate signal line G1 in the first column to the gate signal line G512 in the 512th column are sequentially set to a potential with a quarter delay of one cycle. "high". In addition, each gate signal line is set to "H" during one half of a cycle, and two gate signal lines in subsequent columns are simultaneously set to "H" during one quarter of a cycle.

Here, the display elements in each column are continuously selected in a period in which the scan line driver circuit shifts the selection columns twice. When the data of the display image is input in the second half of the cycle in which the display elements in the row are selected, the displayed image can be updated.

Here, the display element control circuit is in a non-operation state in a period in which the period of the image displayed by the display element corresponding to the second screen region from the first to 512th columns is not updated. That is, the image displayed by the display element in the 513th column to the 1024th column corresponding to the first screen area is not updated and the display element control circuit is in a non-operation state.

The non-operation state of the display element control circuit can be achieved by stopping the clock signal (holding the clock signal at the potential "L") as shown in FIG. 5. It is effective to stop the supply of the power voltage while the clock signal is stopped.

In addition, in the period in which the display element corresponding to the second screen area is not selected, that is, in the period in which the display image is not updated, it is in the stop clock signal and the start pulse signal in the driver circuit on the source supply. In this way, power can be further saved.

In addition, the decoder can be used to save power by replacing the displacement register of the scan line driver circuit.

[Example 2]

In this embodiment, the pixel structures corresponding to FIGS. 2 and 3 described in Embodiment 1 will be described with reference to FIGS. 6, 7, and 8A and 8B. Note that the same reference numerals are used in the descriptions of FIGS. 6, 7, and 8A and 8B to describe the same parts as those in FIGS. 2 and 3.

Figure 6 is an example of a pixel plan view, corresponding to the circuit diagram of Figure 3. In addition, FIG. 8A shows a state before the electrodes of the photodiode are formed. Note that the cross-sectional view taken along the chain line A-B in FIG. 6 and the cross-sectional view taken along the chain line C-D correspond to FIG. 8A.

First, a conductive film is formed over the substrate 230. Then, the gate signal lines 207, 213, and 227, the capacitor wiring 224, the photodiode reset signal line 208, the read signal line 209, and the light sensor are formed through a first photolithography step using a first exposure mask. Reference signal line 212. In this embodiment, a glass substrate is used as the substrate 230.

An insulating film serving as a base film may be provided between the substrate 230 and the conductive film. The base film has a function of preventing diffusion of impurity elements from the substrate 230. The base film may be formed with a single layer structure or a layered structure including one or more of a silicon nitride film, a silicon oxide film, a silicon oxynitride film, and a silicon oxynitride film.

A single-layer structure or a layered structure including a metallic material such as molybdenum, titanium, tantalum, tantalum, tungsten, aluminum, copper, neodymium, or praseodymium or an alloy material containing any of these metallic materials as a main component forms a conductive film.

Next, an insulating layer covering these wirings is formed, and selective etching is performed through a second photolithography step using a second exposure mask to retain the insulating layer 231 only in a portion crossing the subsequently formed wirings. In this embodiment, a silicon oxynitride film having a thickness of 600 nm is used as the insulating layer 231.

Next, a gate insulating layer 232 and an oxide semiconductor film are formed, and then, the first oxide semiconductor layer 233, the second oxide semiconductor layer 253, and the first oxide semiconductor layer are formed through a third photolithography step using a third exposure mask. The trioxide semiconductor layer 255 and the fourth oxide semiconductor layer 256. The first oxide semiconductor layer 233, the second oxide semiconductor layer 253, the third oxide semiconductor layer 255, and the fourth oxide semiconductor layer 256 overlap the gate signal line 227, the gate signal line 207, and the read signal line, respectively. 209 and a gate signal line 213, and a gate insulating layer 232 is disposed therebetween. In this embodiment, a silicon oxynitride film having a thickness of 100 nm is used as the gate insulating layer 232, and an In-Ga-Zn-O film having a thickness of 30 nm is used as the oxide semiconductor layer.

An oxide thin film represented by the chemical formula InMO ₃ (ZnO) _m ( m > 0) can be used as the first oxide semiconductor layer 233, the second oxide semiconductor layer 253, the third oxide semiconductor layer 255, and the fourth oxide物 imonic layer 256. Here, M represents one or more metal elements selected from Ga, Al, Mn, and Co. For example, M may be Ga, Ga and Al, Ga and Mn, Ga and Co, or the like. In addition, SiO ₂ may be contained in the above-mentioned oxide thin film.

As a target for forming an oxide thin film by a sputtering method, for example, an oxide target having a composition ratio of In ₂ O ₃ : Ga ₂ O ₃ : ZnO = 1: 1: 1 [mole ratio] is used for formation. In-Ga-Zn-O film. Without limiting the materials and components of the target, an oxide target having a composition ratio of In ₂ O ₃ : Ga ₂ O ₃ : ZnO = 1: 1: 2 [Moire ratio] can be used. Note that in this specification, for example, the In-Ga-Zn-O film means an oxide film including indium (In), gallium (Ga), and zinc (Zn), and there is no particular limitation on the stoichiometric ratio.

Next, the oxide semiconductor layer is subjected to a first heat treatment. The oxide semiconductor layer can be dehydrated or dehydrogenated by the first heat treatment. The temperature of the first heat treatment is higher than or equal to 400 ° C and lower than or equal to 750 ° C, or higher than or equal to 400 ° C and lower than the strain point of the substrate. In this embodiment, a rapid thermal annealing (RTA) device is used; heat treatment is performed at 650 ° C in a nitrogen surrounding environment for 6 minutes; the substrate is introduced into an electric furnace as one of the heat treatment equipment without being exposed to air; and at 450 ° C at A heat treatment is performed on the oxide semiconductor layer for one hour under a nitrogen surrounding environment. Next, the substrate is transferred into a deposition chamber of the oxide semiconductor layer without being exposed to the air to prevent mixing of water or hydrogen with the oxide semiconductor layer, thereby obtaining an oxide semiconductor layer.

Next, the gate insulation layer 232 is selectively removed through a fourth photolithography step using a fourth exposure mask, so openings reaching the gate signal line 213 and openings reaching the photodiode reset signal line 208 are formed.

Next, a conductive film is formed over the gate insulating layer 232 and the oxide semiconductor layer. A metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, an alloy film containing a nitride of any of these elements, an alloy film containing a combination of any of these elements, or the like can be used A conductive film is formed. In this embodiment, the conductive film has a three-layer structure in which a Ti film having a thickness of 100 nm, an Al film having a thickness of 400 nm, and a Ti film having a thickness of 100 nm are stacked. Next, a fifth photolithography step using a fifth exposure mask is performed to form a resist mask over the conductive film and perform selective etching, thereby forming a video data signal line 210, a light sensor output signal line 211, And electrode layers 234, 235, 254, 257, 258, and 259.

Note that the transistor 221 shown in FIG. 3 includes a first oxide semiconductor layer 233 and an electrode layer 234 serving as a source electrode layer or a drain electrode layer, as shown in FIG. 6. In addition, as shown in FIGS. 6 and 8A, the electrode layer 234, the gate insulating layer 232 serving as a dielectric, and the capacitor wiring 224 form a storage capacitor 222. In addition, as shown in FIG. 6, the transistor 201 includes a second oxide semiconductor layer 253 and an electrode layer 254 serving as a source electrode layer or a drain electrode layer.

In addition, the transistor 206, which is one of the elements included in the photo sensor 106 in FIG. 3, includes a third oxide semiconductor layer 255 and an electrode layer 257 serving as a source electrode layer or a drain electrode layer. Figure 6 shows. In addition, the transistor 205 includes a fourth oxide semiconductor layer 256 and an electrode layer 257 or an electrode layer 258 serving as a source electrode layer or a drain electrode layer, as shown in FIG. 6. As shown in FIG. 8A, the gate signal line 213 of the transistor 205 is electrically connected to the electrode layer 236 through the opening of the gate insulating layer 232.

Next, in the ambient environment of inert gas or oxygen (preferably higher than or equal to 200 ° C and lower than or equal to 400 ° C, for example, higher than or equal to 250 ° C and lower than or equal to 350 ° C) Second heat treatment. In this embodiment, a second heat treatment is performed for one hour at 300 ° C. under a nitrogen surrounding environment. Through the second heat treatment, a part of the oxide semiconductor layer (the channel formation region) is heated while contacting the insulating layer.

Next, an insulating layer 237 to be a protective insulating layer is formed, and an opening to the electrode layer 235, an opening to the electrode layer 234, and an opening to the electrode layer 236 are formed through a sixth photolithography step using a sixth exposure mask. Opening. In this embodiment, a silicon oxide film having a thickness of 300 nm obtained by a sputtering method is used as the insulating layer 237.

Next, p-layer 238, i-layer 239, and n-layer 240 are stacked by a plasma CVD method. In this embodiment, a boron-containing microcrystalline silicon film having a thickness of 60 nm is used as the p-layer 238; an amorphous silicon film having a thickness of 400 nm is used as the i-layer 239; and a phosphorus-containing microcrystal having a thickness of 80 nm is used The silicon film serves as the n-layer 240. The p-layer 238, i-layer 239, and n-layer 240 are selectively etched through a seventh photolithography step using a seventh exposure mask, and further, as shown in FIG. 8A, the periphery of the n-layer 240 is selectively removed. And part of the i-layer 239. Figure 8A is a sectional view to this stage and its plan view corresponds to Figure 6.

Next, an eighth photolithography step of forming a photosensitive organic resin layer is performed, using an eighth exposure mask to expose the area that will be formed as an opening, and using a ninth exposure mask to expose the area having an uneven shape, and performing development, An insulating layer 241 having a part having an uneven shape is formed. In this embodiment, an acrylic resin having a thickness of 1.5 μm is used as the organic resin layer.

Next, a reflective conductive film is deposited, and a ninth photolithography step using a tenth exposure mask is performed to form a reflective electrode layer 242 and a connection electrode layer 243. Note that in FIG. 8B, the reflective electrode layer 242 and the connection electrode layer 243 are shown. As the reflective conductive film, Al, Ag, or an alloy thereof (such as Nd-containing aluminum or Ag-Pd-Cu alloy) is used. In this embodiment, a stack of a Ti film having a thickness of 100 nm and an Al film having a thickness of 300 nm disposed thereon is used as a conductive film having reflectivity. After the ninth light lithography step, a third heat treatment is performed. In this embodiment, a third heat treatment is performed at 250 ° C. for one hour under a nitrogen surrounding environment.

Through the above steps, by using nine photolithography steps using a total of ten exposure masks, a transistor electrically connected to the reflective electrode layer 242 and electrically connected to the gate signal line 213 through the connection electrode layer 243 can be formed over a substrate. Photodiode.

Note that a cross-sectional photograph of a peripheral portion of the photodiode is shown in FIG. 11A. FIG. 11A shows a cross section of the photodiode 204 and FIG. 11B shows a schematic view of the cross section.

An alignment film 244 covering the reflective electrode layer 242 is formed. The sectional view at this stage corresponds to FIG. 8B. It is noted that the same reference numerals are used for common components in Figs. 8B and 11B. Therefore, an active matrix substrate can be manufactured.

Next, an opposite substrate to be bonded to the active matrix substrate is prepared. Above the opposing substrate, a light-blocking layer (also referred to as a black matrix) and a light-transmitting conductive film are formed, and a columnar spacer is formed using an organic resin. Next, alignment films are formed to cover them.

The opposite substrate is attached to the active matrix substrate with a sealant, and a liquid crystal layer is sandwiched between the pair of substrates. The light blocking layer of the opposite substrate is provided so as not to overlap the display area of the reflective electrode layer 242 and the sensing area of the photodiode. The columnar spacers positioned on the opposite substrate are positioned to overlap the electrode layers 251 and 252. Since the columnar spacers overlap the electrode layers 251 and 252, the pair of substrates can be kept at a certain distance. The electrode layers 251 and 252 can be formed in the same steps as the electrode layer 234; therefore, there is no need to increase the number of masks. The electrode layers 251 and 252 are not connected anywhere and are in a floating state.

FIG. 7 is a plan view of pixels in the pair of substrates attached to each other in this manner. In FIG. 7, a region where the black matrix is not overlapped serves as a light receiving region and a reflective electrode region of the light sensor. The area ratio of the reflective electrode in the unit area (120 μm × 240 μm) shown in FIG. 7 was 77.8%. The area of the light receiving area of the light sensor is approximately 1140 μm ² . In addition, since the reflective electrode layer 242 is disposed above the photosensitive organic resin layer having uneven portions, the reflective electrode layer 242 has an irregular planar pattern as shown in FIG. 7. The surface shape of the photosensitive organic resin layer is reflected on the surface of the reflective electrode layer 242, so the surface of the reflective electrode layer 242 has an uneven shape; therefore, specular reflection is prevented. Note that in FIG. 7, the concave portion 245 of the reflective electrode layer 242 is also shown. The periphery of the recessed portion 245 is positioned within the periphery of the reflective electrode layer, and the photosensitive organic resin layer below the recessed portion 245 has a smaller thickness than other regions.

If necessary, an optical film, such as a retardation film, a polarizing film, an anti-reflection film, or a color filter, may be provided on the surface where the external light from the opposite substrate enters.

FIG. 12 shows a photograph of a panel actually manufactured, in which a video signal is input to the panel via FPC to perform display. The screen on one half of the panel displays still images and the other half on the screen displays moving images. Reduces power consumption when a still image is displayed on one half of the panel and a moving image is displayed on the other half. In addition, the keyboard buttons shown in FIG. 1A are displayed by touching the screen with a finger, and data is input by touching the portion of the display keyboard buttons with a finger, whereby the letters corresponding to the keyboard buttons can be displayed on the display area. . In addition, when a light sensor is used and a sufficient amount of external light can be used to sense the shadow of the finger in a non-contact state where the finger is close to the screen but not in contact with the screen, a contactless operation can be performed.

[Example 3]

In this embodiment, an example of a liquid crystal display module with full-color display capability in which color filters are provided will be described.

FIG. 9 illustrates the structure of the liquid crystal display module 190. The liquid crystal display module 190 includes a display panel 120 in which liquid crystal elements are arranged in a matrix, and a polarizing plate and a color filter 115 which overlap the display panel 120. In addition, flexible printed circuits (FPC) 116a and 116b serving as external input terminals are electrically connected to terminal portions provided in the display panel 120. The display panel 120 has the same structure as the display panel 100 described in the first embodiment. It is noted that due to the use of full-color display, the display panel 120 uses three display elements of a red display element, a green display element, and a blue display element, and has a circuit in which individual video signals different from each other are supplied to the three display elements. configuration.

In addition, FIG. 9 schematically illustrates a state in which the transmitted external light 139 passes through the liquid crystal element above the display panel 120 and is reflected at the reflective electrode. For example, in pixels in the red area of the overlapping color filter, external light 139 is transmitted through the color filter 115 and then through the liquid crystal layer, is reflected at the reflective electrode, and is transmitted again through the color filter 115 to be extracted into red light. . FIG. 9 schematically illustrates light rays 135 of three colors by arrows (R, G, and B). The intensity of the light transmitted through the liquid crystal element is modulated by the image signal. Therefore, the viewer can capture the image by the reflected light of the external light 139.

In addition, the display panel 120 includes a light sensor and has a touch input function. When the color filter also overlaps the light receiving area of the light sensor, the display panel 120 has a function of a visible light sensor. In addition, in order to improve the light sensitivity of the light sensor, a large amount of incident light is incorporated. Therefore, an opening may be provided in the color filter in a region overlapping the light receiving region of the light sensor so that the light receiving region of the light sensor and the color filter do not overlap each other.

This embodiment can be freely combined with Embodiment 1 or Embodiment 2.

[Example 4]

In this embodiment, an example of an electronic device including the liquid crystal display device described in any of the above embodiments will be described.

FIG. 10A illustrates an e-book reader (also referred to as an e-book reader), which may include a housing 9630, a display portion 9631, operation keys 9632, a solar cell 9633, and a charge and discharge control circuit 9634. The e-book reader is provided with a solar cell 9633 and a display panel, so the solar cell 9633 and a display panel can be freely opened and closed. In the e-book reader, power is supplied from a solar cell to a display panel or a video signal processing section. The e-book reader shown in FIG. 10A may have a function of displaying various data (such as still images, moving images, and text images), a function of displaying calendar, data, time, or the like on the display section, borrowing A touch input function that operates or edits information displayed on the display by a touch input, a function that controls processing by various software (programs), and the like. Note that in FIG. 10A, the structure including the battery 9635 and the DCDC converter (hereinafter referred to as the converter 9636) is shown as an example of the charge and discharge control circuit 9634.

The display portion 9631 is a reflective liquid crystal display device having a touch function using a light sensor, and is used in a relatively bright environment. Therefore, the structure shown in FIG. 10A is preferable because the power generation from the solar cell 9633 and the charging in the battery 9635 can be performed efficiently. It is noted that a structure in which a solar cell 9633 is provided on each of the surface and the back surface of the housing 9630 is preferable in order to efficiently charge the battery 9635. When a lithium-ion battery is used as the battery 9635, there are advantages such as downsizing or the like.

The structure and operation of the charge and discharge control circuit 9634 shown in FIG. 10A are described with reference to the block diagram in FIG. 10B. FIG. 10B shows the solar cell 9633, the battery 9635, the converter 9636, the converter 9637, the switches SW1 to SW3, and the display portion 9631, and the battery 9635, the converter 9636, the converter 9637, and the switches SW1 to SW3. Corresponds to the charge and discharge control circuit 9634.

First, an example of the operation in a case where power is generated by the solar cell 9633 using external light will be described. The converter 9636 raises or lowers the voltage of the power generated by the solar cell, so that the power has the voltage of the rechargeable battery 9635. Next, when the power from the solar cell 9633 is used for the operation of the display portion 9631, the switch SW1 is turned on and the voltage of the power is raised or lowered by the converter 9637 to become the voltage required by the display portion 9631. In addition, when the display on the display portion 9631 is not performed, the switch SW1 is turned off and the switch SW2 is turned on to perform charging of the battery 9635.

Note that although the solar cell 9633 is described as an example of the charging mechanism, the charging of the battery 9635 may be performed by another mechanism. In addition, a combination of a solar cell 9633 and another mechanism for charging may be used.

This embodiment can be implemented in appropriate combination with any of the structures described in the other embodiments.

[Example 5]

In this embodiment, an example is described in which a transistor and a light sensor are formed over a glass substrate and transferred and mounted on a flexible substrate. Note that here, cross-sectional views of the step of forming a transistor are shown in FIGS. 13A to 13C. In FIGS. 13A to 13C, detailed descriptions of the same steps and structures of the light sensor as those of Embodiment 2 are omitted, and the same portions as those of FIGS. 8A and 8B are designated by the same reference symbols.

First, a separation layer 260 is deposited on the substrate 230 by a sputtering method, and an oxide insulating film 261 serving as a base film is formed thereon. Note that as the substrate 230, a glass substrate, a quartz substrate, or the like can be used. By PVCD method, sputtering method, or the like, such as silicon oxide, silicon oxynitride (SiO _x N _y ) (x>y> 0), or silicon oxynitride (SiN _x O _y ) (x>y> 0) to form the oxide insulating film 261.

The separation layer 260 may be formed using a layered structure of a metal film, a metal film, and a metal oxide film, or the like. As the metal film, tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), zirconium (Zr), zinc (Zn), A film formed of an element of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir) or a film formed using an alloy material or a compound material containing the element as a main component Single or stacked layers. For example, when a tungsten film is provided as a metal film by a sputtering method, a CVD method, or the like, a metal oxide film formed of tungsten oxide can be formed on the surface of the tungsten film by applying a plasma treatment to the tungsten film. . In addition, for example, after forming a metal film (such as tungsten), an insulating film formed of silicon oxide or the like can be formed over the metal film by sputtering, and a metal oxide (such as in Tungsten oxide on tungsten). In addition, a high-density plasma treatment using a high-density plasma equipment can be performed as the plasma treatment. In addition, in addition to the metal oxide film, a metal nitride film or a metal oxynitride film may be used. In this case, plasma treatment or heat treatment is performed on the metal film in a nitrogen surrounding environment or a surrounding environment of nitrogen and oxygen.

Next, a conductive film is formed over the oxide insulating film 261. Next, in a manner similar to Embodiment 2, a gate signal line 227, a capacitor wiring 224, a photodiode reset signal line, a read signal line, and light are formed through a first photolithography step using a first exposure mask. Sensor reference signal line.

The subsequent steps are performed according to Embodiment 2 to form a transistor and a reflective electrode layer 242. Next, the reflective electrode layer 242 is covered with a water-soluble resin layer 262. Figure 13A is a cross-sectional view at this stage. Note that for simplicity, the cross-sectional structure of the periphery of the reflective electrode layer 242 is shown in FIG. 13A but the photodiodes formed on the same substrate are not shown.

Next, the water-soluble resin layer 262 is fixed to a support substrate or the like, and an opening is formed by irradiating the separation layer with laser light or the like, thereby separating the layer including the transistor from the substrate 230. Figure 13B is a sectional view at this stage. As shown in FIG. 13B, separation is performed at the interface between the separation layer 260 provided with the substrate 230 and the oxide insulating film 261.

Next, as shown in FIG. 13C, the flexible substrate 264 is attached to the surface of the layer including the transistor by the adhesive layer 263 (the surface from which the external storm is separated). As the flexible substrate 264, a plastic film or a thin stainless steel substrate can be used.

Next, the water-soluble resin layer 262 is removed and an alignment film 244 is formed. Next, a counter substrate 268 and a flexible substrate 264 including a counter electrode 267 are attached to each other. Note that before the attachment, an alignment film 266 is formed for the opposite substrate 268 to cover the opposite electrode 267. In the case of using the liquid crystal dropping method, the liquid crystal is dropped onto an area surrounded by a sealant of a closed loop and the attachment of the pair of substrates is performed under reduced pressure. In this manner, a region surrounded by the pair of substrates and the sealant is filled with the liquid crystal layer 265. When a plastic film with high light transmission properties and small retardation is used as the opposite substrate 268, a flexible liquid crystal panel can be manufactured.

The above procedure for manufacturing a flexible liquid crystal panel is only an example. Alternatively, for example, the flexible liquid crystal panel may be manufactured in such a manner that the glass substrate as the substrate 230 and the opposite substrate 268 is used by grinding or thinning after the transistor is manufactured. In the case of thinning by grinding, both the substrate 230 and the opposing substrate 268 are thinned by grinding after the filling with the liquid crystal layer is performed.

14A and 14B illustrate an example of an e-book reader using a liquid crystal panel.

FIGS. 14A and 14B illustrate a case where a support portion 4308 is provided at an end portion of the liquid crystal panel 4311 as an example of an e-book reader. The specific structure of the e-book reader will be described below with reference to FIGS. 14A and 14B. FIG. 14A illustrates an e-book reader placed horizontally, and FIG. 14B illustrates an e-book reader placed vertically.

The e-book reader shown in FIGS. 14A and 14B includes a flexible liquid crystal panel 4311 including a display portion 4301, a support portion 4308 provided at an end portion of the liquid crystal panel 4311, and scanning control for controlling the display of the display portion 4301. A line driver circuit 4321a, a light sensor driver circuit 4321b for controlling a photodiode provided in the display section 4301, and a signal line driver circuit 4323 for controlling a display of the display section 4301.

The scan line driver circuit 4321a and the photo sensor driver circuit 4321b are disposed on a flexible surface of the liquid crystal panel 4311, and the signal line driver circuit 4323 is disposed within the support portion 4308.

The preferred support portion 4308 is less flexible (harder) than at least the liquid crystal panel 4311. For example, a casing of the supporting portion 4308 formed by using a thicker plastic, metal, or the like than the liquid crystal panel 4311 may be used. In that case, the e-book reader may be folded (bent) in a portion outside the non-supporting portion 4308.

There is no particular limitation on where the support portion 4308 is provided. For example, a support portion 4308 may be provided along an end portion of the liquid crystal panel 4311. For example, as shown in FIGS. 14A and 14B, in a case where the liquid crystal panel 4311 has a rectangular shape, a support portion 4308 may be provided along a predetermined side of the liquid crystal panel 4311 (so that side is fixed). Note that the "rectangular shape" includes the rounded corners of the rectangle.

In addition, when the scan line driver circuit 4321a, the photo sensor driver circuit 4321b, and the pixel circuit included in the display portion 4301 are formed over the flexible substrate through the same procedure, the scan line driver circuit 4321a and the light can be concavely folded. The sensor driver circuit 4321b can also achieve cost reduction.

A thin film transistor or the like may be used to form a pixel circuit included in the display portion 4301 and elements included in the scan line driver circuit 4321a and the photo sensor driver circuit 4321b. On the other hand, an integrated circuit (IC) formed using a semiconductor substrate such as a silicon substrate or an SOI substrate may be used to form a high-speed operation circuit such as a signal line driver circuit 4323, and the IC may be provided in the support portion 4308.

A flexible substrate is used to form the liquid crystal panel 4311, and therefore, thanks to the touch input using a photodiode, data can be inputted without any problem even with a concave folding screen. Therefore, the operability of the liquid crystal panel 4311 is better than that of other electronic devices having a touch input system.

Note that an example in which a metal layer is used as the separation layer is shown in this embodiment, but the embodiment is not limited thereto. A separation method using peeling by laser irradiation, a separation method using organic resin, or the like can be used.

[Example 6]

In this embodiment, an example of a structure of a scan line driver circuit of a liquid crystal panel is described with reference to the drawings.

FIG. 15 is a block diagram of the driver circuit described in this embodiment. In the case where a driver circuit is used as a gate driver (scanning line driver circuit) of the VGA, 480 gate lines must be driven, and therefore, a 9-bit data line is required. In this example, a 3-bit example is described.

Block 701 indicates the circuit that generates the first-level gate signal, block 702 indicates the circuit that generates the second-level gate signal, block 703 indicates the circuit that generates the third-level gate signal, and block 704 indicates generation The fourth-level gate signal circuit, and block 705 indicates the circuit that generates the fifth-level gate signal. In the case of VGA, in addition to the above, there are blocks that generate gate signals of levels 6 to 480.

Data0a, Data0b, Data1a, Data1b, Data2a, and Data2b indicate data lines. Any character from 0 to 2 that is the second to last character of the signal name corresponds to 3-bit data. For the last characters "a" and "b" of the signal name, "b" corresponds to the opposite signal of "a" but not the exact opposite signal. During periods of no data input, Data0a to Data2b are set to 0 (low, also known as GND). The method of connecting data lines and blocks in individual levels is as follows: When the first level represents the binary "001", since Data0a and Data0b corresponding to the lowest bit and lowest bit of the first level are "1"; Therefore, the first-level block is connected to the one whose last character is "b", that is, Data0b. In a similar manner, since the bit immediately following the lowest bit is "0", the first level is connected to the one whose last character is "a", that is, Data1a.

Figure 16 shows the relationship between time-related data lines. In period 1 in which the first-level block 701 is selected, Data2a is set to 0 (low), Data1a is set to 0 (low), and Data0a is set to 1 (high), which corresponds to "001", which is 1 The binary representation. In the period 2 in which the second-level block 702 is selected, Data2a is set to 0 (low), Data1a is set to 1 (high), and Data0a is set to 0 (low), which corresponds to "010", which is 2 The binary representation. For the third and subsequent levels, the data is also determined in the same way.

In addition, when Data0a is 0 (low), Data0b corresponding to it is set to 1 (high), and when Data0a is 1 (high), Data0b is set to 0 (low). The same relationship between Data1a and Data2a applies to Data1b and Data2b. Note that a period in which Data0a and Data0b are both 0 (low) is inserted between period 1 in which block 701 of the first level is selected and period 2 in which block 702 of the second level is selected and acts as no input data Period.

FIG. 17 is a diagram of an internal circuit forming the block 701. The same applies to the circuits forming blocks 702, 703, 704, and 705. Also in Fig. 17, a 3-bit example is described. An n-channel transistor group 802, an n-channel transistor 803, an n-channel transistor 804, and an n-channel transistor group 806 shown in FIG. 17 are formed on the same substrate as the transistor of the display section. An oxide semiconductor layer is used as a channel in each of the transistor group and the transistor.

Data0 in Figure 15 and Data0 in Figure 17 correspond to each other, and Data0 is electrically connected to Data0a and Data0b in Figure 15. The node 801 has a function of holding data. Although the data can be held by the capacitor, since the parasitic capacitance is acceptable, the capacitor for holding the data is omitted in this embodiment. When one of the data lines Data0 to Data2 is set to 1 (high), one of the transistors of the n-channel transistor group 802 is turned on and the node 801 is set to 0 (low). When all data lines Data0 to Data2 are 0 (low), node 801 remains at 1 (high) and this block is considered to be selected. In addition, when there is no input data, all data lines Data0 to Data2 are set to 0 (low) and all transistor groups 802 are turned off.

In order to set the node 801 to 1 (high), the reset signal is set to 1 (high), thereby turning on the transistor 803 which is an n-channel transistor. Note that even when the transistor 803 is turned on, the node 801 does not always have the same potential as VDD because of the threshold value of the transistor 803, which does not cause a problem. When the period in which the reset signal is 1 (high) does not overlap with the period in which one of the data lines Data0 to Data2 is 1 (high), an increase in the current flowing from the power source VDD to GND can be prevented.

When all data lines in the data input period are 0 (low), that is, when a block is selected, the node 801 remains at 1 (high) and the transistor 804 is turned on as an n-channel. In addition, when this block is selected, the node 801 is not electrically connected to the power sources VDD and GND. When the write signal is changed from 0 (low) to 1 (high), the potential of the node 801 is raised due to the capacitive coupling of the capacitor 805. The circuit of the capacitor 805 is called a bootstrap circuit.

After being raised, the potential of the node 801 is preferably higher than the potential obtained by adding the threshold value of the transistor 804 to the highest potential of the write signal. After increasing the potential of node 801, if the potential of node 801 is higher than the potential obtained by adding the threshold of transistor 804 to the highest potential of the write signal, capacitor 805 or parasitic capacitance is not required in some cases For enough.

After the potential of the node 801 is raised, in the case where the potential of the node 801 is lower than the potential obtained by adding the threshold value of the transistor 804 to the highest potential of the write signal, the potential of the node Out does not increase Possibility of writing the highest potential of the signal and not immediately performing pixel writing. When the potential of node 801 is higher than the potential obtained by adding the threshold of transistor 804 to the highest potential of the write signal, the write signal changes from 0 (low) to 1 (high), and the node Out also changes from 0 (low) changes to 1 (high). Node Out is connected to the gate line of the pixel. Next, when the write signal is changed from 1 (high) to 0 (low), the potential of the node 801 is lowered due to the capacitive coupling of the capacitor 805; however, the potential of the node 801 is almost equal to the potential supplied by the reset signal The potential of VDD does not turn off the transistor 804. In other words, since the potential of the node 801 is higher than the potential obtained by adding the threshold value of the transistor 804 to the 0 (low) level of the write signal, the node Out is also 0 (low).

When one of the data lines is 1 (high) in the period of data input, that is, when a block is not selected, the node 801 is 0 (low) and the transistor 804 is turned off.

Even when the write signal is changed from 0 (low) to 1 (high), since the crystal group 802 is turned on, the potential of the node 801 is 0 (low) and the transistor 804 is turned off. Because when the transistor group 802 has a low ability to pass current, the potential of the node 801 is raised due to the capacitive coupling of the capacitor 805; therefore, the ability of the transistor group 802 to pass the current must be judged so that the node Change to small.

Next, even when the write signal is changed from 1 (high) to 0 (low), since the crystal group 802 is turned on, the potential of the node 801 is 0 (low) and the transistor 804 is turned off. When the transistor group 802 has a low passing current capacity, the potential of the node 801 is lowered due to the capacitive coupling of the capacitor 805; therefore, the ability of the transistor group 802 to pass current must be judged so that the node Out changes to small.

In the case where the transistor group 806 is not set, when one of the data lines is 1 (high) in the period of data input, that is, when a block is not selected, the node Out is not electrically connected to a power source and is not affected by video. The effect of the signal. The potential of the node Out is also changed by the capacitive coupling between the source electrode and the drain electrode of the transistor 804. Therefore, in the period in which the transistor 804 is turned off, the node Out is preferably fixed at 0 (low).

Fig. 18 is a graph of time and potential of a node. The operation with respect to the circuit diagram of FIG. 17 will be described using FIG. 18.

In period 901, node 801 is set to 1 (high) by a reset signal. In the period 901, although the crystal 804 is turned on, the write signal is 0 (low) and therefore, the potential of the node Out is also 0 (low). The next period 902 is a period until data input, in which the reset signal is set to 0 (low). It is preferable to prevent the increase in current flowing from the power source VDD to GND by providing the period 902.

The next period 903 is required to judge the potential of the node 801 by inputting data, and a case where all data lines Data0 to Data2 are set to 0 (low) is described here. At the beginning of the next period 904, the write signal is set to 1 (high) and the potential of the node 801 is raised. In period 904, the potential of the node Out is also set to 1 (high).

In the next period 905, the write signal is set to 0 (low). Although the potential of the node 801 is also reduced, the potential of the node Out is 0 (low) because the crystal 804 is turned on. In the next period 906, the period of data input is terminated, and in the next period 907, the reset signal is set to 1 (high) again and the potential of the node 801 is set to 1 (high). The above is a horizontal period, and thereafter, the horizontal period is repeated. The period set by the period 908 instead of the period 903 and in which one of the data lines Data0 to Data2 is set to 1 (high). In period 908, when one of the data lines Data0 to Data2 is set to 1 (high), the potential of the node 801 is set to 0 (low). If the period 908 is short and the write signal is set to 1 (high) in the next period 909 before the potential of the node 801 is sufficiently reduced by turning off the transistor 804, there is no way to fix it by only the transistor group 806 The possibility that the potential of the node Out will temporarily increase. If the transistor 804 is turned off in the period 908, the node Out can remain at 0 (low) even when the write signal is set to (high) in the next period 909. Note that because of the parasitic capacitance between the source electrode and the drain electrode of the transistor 804, even when the transistor 804 is turned off, the potential of the node Out tends to increase. The potential of the node Out must be adjusted by the transistor group 806 so as not to turn on the pixel transistor. The gate line is heavily loaded, and therefore, parasitic capacitance between the source electrode and the drain electrode does not cause a great problem.

In this embodiment, "1 (high)" is described as a potential of VDD and "0 (low)" is described as a potential of GND. When the highest potential of the write signal is lower than VDD, a bootstrap circuit is not needed, but it is not desirable to provide two kinds of power sources externally, because it will increase the cost. In this embodiment, a power source can be used to perform the operation.

Note that the structure of the driver circuit of the display device described in this embodiment can be implemented freely in combination with any structure in other embodiments in this specification.

In the structure of the driver circuit of the display device described in this embodiment, when the write signal and each data line are set to 0 (low) and the reset signal is set to 1 (high), the gates of all pixels The line is set to 0 (low). Unlike the case where the shift register circuit is used for the driver circuit of the display section, the gate lines of the pixels in any column can be set to 1 (high) in any order.

This embodiment is an example of the decoder circuit included in the driver circuit, and therefore, the embodiment is not limited to the structure of the driver circuit of the display device described in this embodiment.

This application is based on Japanese Patent Application Serial No. 2010-050947 filed with the Japan Patent Office on March 8, 2010, the entire contents of which are hereby incorporated by reference.

100. ． ． Display panel

101. ． ． Pixel circuit

103. ． ． Pixel

104. ． ． Pixel

105. ． ． Display element

106. ． ． Light sensor

107. ． ． Display element driver circuit on signal line side

108. ． ． Display element driver circuit on scan line driver circuit

109. ． ． Light sensor reading circuit

110. ． ． Light sensor driver circuit

115. ． ． Color filter

116a. ． ． Flexible printed circuit

116b. ． ． Flexible printed circuit

120. ． ． Display panel

125. ． ． Display element

135. ． ． Light

139. ． ． External light

190. ． ． LCD display module

201. ． ． Transistor

202. ． ． Storage capacitor

203. ． ． Liquid crystal element

204. ． ． Photodiode

205. ． ． Transistor

206. ． ． Transistor

207. ． ． Gate signal line

208. ． ． Photodiode reset signal cable

209. ． ． Signal line

210. ． ． Video data signal cable

211. ． ． Light sensor output signal line

212. ． ． Light sensor reference signal line

213. ． ． Gate signal line

214. ． ． Capacitor wiring

221. ． ． Transistor

222. ． ． Storage capacitor

223. ． ． Liquid crystal element

224. ． ． Capacitor wiring

227. ． ． Gate signal line

230. ． ． Substrate

231. ． ． Insulation

232. ． ． Gate insulation

233. ． ． Oxide semiconductor layer

234. ． ． Electrode layer

235. ． ． Electrode layer

236. ． ． Electrode layer

237. ． ． Insulation

238. ． ． p layer

239. ． ． i layer

240. ． ． n layers

241. ． ． Insulation

242. ． ． Reflective electrode layer

243. ． ． Connecting electrode layer

244. ． ． Alignment film

245. ． ． Recess

251. ． ． Electrode layer

253. ． ． Oxide semiconductor layer

254. ． ． Electrode layer

255. ． ． Oxide semiconductor layer

256. ． ． Oxide semiconductor layer

257. ． ． Electrode layer

258. ． ． Electrode layer

260. ． ． Separation layer

261. ． ． Oxide insulating film

262. ． ． Resin layer

263. ． ． Adhesive layer

264. ． ． Substrate

265. ． ． Liquid crystal layer

266. ． ． Alignment film

267. ． ． Counter electrode

268. ． ． Opposite substrate

701. ． ． Block

702. ． ． Block

703. ． ． Block

704. ． ． Block

705. ． ． Block

801. ． ． node

802. ． ． Transistor group

803. ． ． Transistor

804. ． ． Transistor

805. ． ． Capacitor

806. ． ． Transistor group

901. ． ． period

902. ． ． period

903. ． ． period

904. ． ． period

905. ． ． period

906. ． ． period

907. ． ． period

908‧‧‧ period

909‧‧‧ period

1030‧‧‧Electronic device

1031‧‧‧ button

1032‧‧‧Display

1033‧‧‧area

1034‧‧‧Switch

1035‧‧‧Power Switch

1036‧‧‧Keyboard display switch

4301‧‧‧Display

4308‧‧‧Support

4311‧‧‧LCD Panel

4321a‧‧‧scan line driver circuit

4321b‧‧‧Light sensor driver circuit

4323‧‧‧Signal line driver circuit

9630‧‧‧shell

9631‧‧‧Display

9632‧‧‧operation keys

9633‧‧‧Solar Cell

9634‧‧‧Charge and discharge control circuit

9635‧‧‧battery

9636‧‧‧converter

9637‧‧‧ converter

In the drawings:

1A and 1B are external views illustrating an embodiment of the present invention;

FIG. 2 is a block diagram illustrating an embodiment of the present invention;

FIG. 3 is an equivalent circuit diagram of a pixel, showing an embodiment of the present invention;

FIG. 4 is a schematic diagram of a driver circuit of a light sensor, illustrating an embodiment of the present invention;

FIG. 5 is a timing chart showing an embodiment of the present invention;

FIG. 6 is a plan view of a pixel, illustrating an embodiment of the present invention;

FIG. 7 is an example of a plan view showing a positional relationship between a reflective electrode and a black matrix, and illustrates an embodiment of the present invention; FIG.

8A and 8B are examples of cross-sectional views illustrating an embodiment of the present invention;

FIG. 9 is a schematic diagram of a liquid crystal display module, illustrating an embodiment of the present invention;

10A and 10B are external views and block diagrams of a display device according to an embodiment of the present invention;

11A and 11B are photographs and schematic diagrams of a section of a part of a photodiode;

FIG. 12 is a photo showing the state of a display panel displaying an image;

13A to 13C are examples of cross-sectional views illustrating an embodiment of the present invention;

14A and 14B are schematic diagrams of an e-book reader, illustrating an embodiment of the present invention;

FIG. 15 is a block diagram of a driver circuit, showing an embodiment of the present invention;

Figure 16 shows the relationship between time-related data lines;

Figure 17 is a diagram of the internal circuits forming the block; and

Figure 18 shows the time and individual potentials of the nodes.

Claims (5)

A display device with a touch input function includes a first transistor, a second transistor, and a light sensor above a flexible substrate, wherein one of a source electrode and a drain electrode of the first transistor Electrically connected to a first reflective electrode, wherein the other of the source electrode and the drain electrode of the first transistor are electrically connected to a video data signal line, wherein the source electrode and the drain electrode of the second transistor are electrically connected One is electrically connected to the second reflective electrode, wherein the other of the source electrode and the drain electrode of the second transistor is electrically connected to the video data signal line, wherein the light sensor includes: a photodiode A third transistor whose gate electrode is electrically connected to one of the electrodes of the photodiode; and a fourth transistor where the other electrode of the photodiode is electrically connected to a photodiode whose voltage is variable A signal line, wherein one of the source electrode and the drain electrode of the third transistor is electrically connected to the photo sensor reference signal line, and the other of the source electrode and the drain electrode of the third transistor Electrically connected to the source of the fourth transistor One of an electrode and a drain electrode, wherein the source electrode of the fourth transistor and the other of the drain electrode are electrically connected to a light sensor output signal line parallel to the video data signal line, and wherein The oxide semiconductor layer of the fourth transistor overlaps the first reflective electrode. The display device according to item 1 of the scope of patent application, wherein the oxide semiconductor layer of the third transistor overlaps the read signal line, and a gate insulating layer is disposed therebetween, and wherein the read signal line overlaps The first reflective electrode. The display device according to item 1 of the scope of patent application, wherein one of the source electrode and the drain electrode of the fourth transistor overlaps the first reflective electrode and the source electrode and the fourth transistor of the fourth transistor The other of the drain electrodes overlaps the second reflective electrode. A display device with a touch input function includes a first transistor and a light sensor above a flexible substrate, wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to a first reflection An electrode, wherein the other of the source electrode and the drain electrode of the first transistor are electrically connected to a video data signal line, wherein the light sensor includes: a photodiode; and a gate electrode thereof is electrically connected to the A second transistor of one electrode of the photodiode; and a third transistor, and the other electrode of the photodiode is electrically connected to a photodiode reset signal line whose voltage is variable, wherein the second transistor One of the source electrode and the drain electrode of the crystal is electrically connected to a light sensor reference signal line parallel to the photodiode reset signal line, wherein the source electrode and the drain electrode of the second transistor are The other is electrically connected to one of a source electrode and a drain electrode of the third transistor, and wherein the other of the source electrode and the drain electrode of the third transistor is electrically connected to a photo sensor Output signal line. The display device according to item 4 of the scope of patent application, wherein the oxide semiconductor layer of the second transistor overlaps the read signal line, and a gate insulating layer is disposed therebetween, and wherein the read signal line overlaps The first reflective electrode.